Android Multi_User 添加新用户源码分析

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PackageManagerService

1，首先看UserManager中的createUser函数，他是创建新用户的入口

public UserInfo createUser(String name, int flags) {
try {
//调用UserManagerService的createUser方法
return mService.createUser(name, flags);
} catch (RemoteException re) {
Log.w(TAG, "Could not create a user", re);
return null;
}
}

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由上可知，该段代码主要功能就是调用了UserManagerService的对应的createUser函数。

2，下面我们重点分析一下UserManagerService的createUser方法

@Override
public UserInfo createUser(String name, int flags) {
//权限检查
checkManageUsersPermission("Only the system can create users");
final long ident = Binder.clearCallingIdentity();
final UserInfo userInfo;
try {
synchronized (mInstallLock) {
synchronized (mPackagesLock) {
//如果当前用户数，已经到达支持数目，则停止创建新用户
if (isUserLimitReachedLocked()) return null;
//生成用户ID
int userId = getNextAvailableIdLocked();
//创建一个userInfo实例
userInfo = new UserInfo(userId, name, null, flags);
//指向“data/user/userId”文件夹
File userPath = new File(mBaseUserPath, Integer.toString(userId));
//mNextSerialNumber就是UserManagerService的构造函数中读取到的
userInfo.serialNumber = mNextSerialNumber++;
long now = System.currentTimeMillis();
userInfo.creationTime = (now > EPOCH_PLUS_30_YEARS) ? now : 0;
//该值为true，表明用户尚未创建成功
userInfo.partial = true;
//为新用户创建“data/system/users/userId”目录
Environment.getUserSystemDirectory(userInfo.id).mkdirs();
//将新用户添加到mUsers 中
mUsers.put(userId, userInfo);
//将新用户信息写入到“data/system/users/userlist.xml”之中
writeUserListLocked();
//将新用户信息写入到“data/system/users/userId.xml”之中
writeUserLocked(userInfo);
mPm.createNewUserLILPw(userId, userPath);
//新用户创建成功
userInfo.partial = false;
//更新新用户的partial属性为false，更新“data/system/users/userId.xml”
writeUserLocked(userInfo);
//更新mUserIds数组
updateUserIdsLocked();
//这是用户限制“restrictions”相关的内容，将在其他地方讲解
Bundle restrictions = new Bundle();
mUserRestrictions.append(userId, restrictions);
}
}
if (userInfo != null) {
//发送广播Intent.ACTION_USER_ADDED
//同时此广播附带Intent.EXTRA_USER_HANDLE类型的userInfo.id消息，
//便于接收到广播的组件读取用户ID
Intent addedIntent = new Intent(Intent.ACTION_USER_ADDED);
addedIntent.putExtra(Intent.EXTRA_USER_HANDLE, userInfo.id);
mContext.sendBroadcastAsUser(addedIntent, UserHandle.ALL,
android.Manifest.permission.MANAGE_USERS);
}
} finally {
Binder.restoreCallingIdentity(ident);
}
return userInfo;
}

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由上面代码可知，UserManagerService的createUser方法主要工作如下：
A，检查当前用户数是否已达上限，如是则停止创建新用户
B，创建新用户userInfo
C，准备创建“data/user/userId”文件夹
D，为新用户创建“data/system/users/userId”文件夹
E，将新用户信息写入到“data/system/users/userlist.xml”文件中
F，将新用户信息写入到“data/system/users/userId.xml”文件之中
G，调用PackageManagerService的createNewUserLILPw，此方法很重要，将在后面重点讲解。此方法首先创建“data/user/userId”文件夹，然后将新用户可以使用的App从“system/app”等地方的APP复制一份到“data/user/userId”文件夹下
H，用户正式创建成功，userInfo.partial值为false，更新“data/system/users/userId.xml”
I，发送Intent.ACTION_USER_ADDED广播，附带了新用户的userId

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沙发

发表于 2014-1-16 18:29:03 |只看该作者

3，下面看看writeUserListLocked函数所写的“data/system/users/userlist.xml”的格式

/**
* <?xml version="1.0" encoding="utf-8" standalone="yes" ?>
* - <users nextSerialNumber="11" version="2">
* <user id="0" />
* <user id="10" />
* </users>
*/

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具体，可自行从你的安卓设备中下载查看。

4，下面再看看writeUserLocked函数所写的“data/system/users/userId.xml”文件的格式

/**
* <?xml version="1.0" encoding="utf-8" standalone="yes" ?>
* - <user id="11" serialNumber="14" flags="16" created="1388534774982"
* lastLoggedIn="1388534863493" icon="/data/system/users/11/photo.png">
* <name>新用户</name>
* <restrictions />
* </user>
*/

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5，下面重点分析PackageManagerService的createNewUserLILPw方法

void createNewUserLILPw(int userHandle, File path) {
if (mInstaller != null) {
mSettings.createNewUserLILPw(this, mInstaller, userHandle, path);
}
}

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A，该方法调用了Settings中的createNewUserLILPw方法

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板凳

发表于 2014-1-16 18:32:17 |只看该作者

6，下面看一下Settings的createNewUserLILPw函数

void createNewUserLILPw(PackageManagerService service, Installer installer,
int userHandle, File path) {
//创建“data/user/userId”文件夹
path.mkdir();
FileUtils.setPermissions(path.toString(), FileUtils.S_IRWXU | FileUtils.S_IRWXG
| FileUtils.S_IXOTH, -1, -1);
for (PackageSetting ps : mPackages.values()) {
// Only system apps are initially installed.
//存放在"system/app"文件夹下的app都属于系统应用
//他们都具有这样的属性：(ps.pkgFlags&ApplicationInfo.FLAG_SYSTEM) != 0
//将所有"system/app"文件夹下的app的PackageUserState的installed属性置为true
ps.setInstalled((ps.pkgFlags&ApplicationInfo.FLAG_SYSTEM) != 0, userHandle);
// Need to create a data directory for all apps under this user.
installer.createUserData(ps.name,
UserHandle.getUid(userHandle, ps.appId), userHandle);
}
// 从”etc/preferred-apps”目录下的XML文件
readDefaultPreferredAppsLPw(service, userHandle);
// 写当前用户的“data/system/users/userId/package-restrictions.xml”文件
writePackageRestrictionsLPr(userHandle);
}

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A，该方法首先将所有“system/app”文件夹下的系统应用的installed属性设置为true
B，然后调用Installer.java中的createUserData函数
C，读取”etc/preferred-apps”目录下的XML文件
D，写入当前用户的“data/system/users/userId/package-restrictions.xml”文件

7，下面我们重点看看writePackageRestrictionsLPr函数，该函数源码如下

void writePackageRestrictionsLPr(int userId) {
if (DEBUG_MU) {
Log.i(TAG, "Writing package restrictions for user=" + userId);
}
// Keep the old stopped packages around until we know the new ones have
// been successfully written.
//指向文件“data/system/users/userId/package-restrictions.xml”
File userPackagesStateFile = getUserPackagesStateFile(userId);
//指向文件“data/system/users/userId/package-restrictions-backup.xml”
File backupFile = getUserPackagesStateBackupFile(userId);
new File(userPackagesStateFile.getParent()).mkdirs();
if (userPackagesStateFile.exists()) {
// Presence of backup settings file indicates that we failed
// to persist packages earlier. So preserve the older
// backup for future reference since the current packages
// might have been corrupted.
if (!backupFile.exists()) {
if (!userPackagesStateFile.renameTo(backupFile)) {
Log.wtf(PackageManagerService.TAG, "Unable to backup user packages state file, "
+ "current changes will be lost at reboot");
return;
}
} else {
userPackagesStateFile.delete();
Slog.w(PackageManagerService.TAG, "Preserving older stopped packages backup");
}
}
try {
final FileOutputStream fstr = new FileOutputStream(userPackagesStateFile);
final BufferedOutputStream str = new BufferedOutputStream(fstr);
final XmlSerializer serializer = new FastXmlSerializer();
serializer.setOutput(str, "utf-8");
serializer.startDocument(null, true);
serializer.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true);
//XML标记：package-restrictions
serializer.startTag(null, TAG_PACKAGE_RESTRICTIONS);
for (final PackageSetting pkg : mPackages.values()) {
PackageUserState ustate = pkg.readUserState(userId);
if (ustate.stopped || ustate.notLaunched || !ustate.installed
|| ustate.enabled != COMPONENT_ENABLED_STATE_DEFAULT
|| ustate.blocked
|| (ustate.enabledComponents != null
&& ustate.enabledComponents.size() > 0)
|| (ustate.disabledComponents != null
&& ustate.disabledComponents.size() > 0)) {
//XML标记：pkg
serializer.startTag(null, TAG_PACKAGE);
//XML标记：name
serializer.attribute(null, ATTR_NAME, pkg.name);
if (DEBUG_MU) Log.i(TAG, " pkg=" + pkg.name + ", state=" + ustate.enabled);
if (!ustate.installed) {
//XML标记：inst
serializer.attribute(null, ATTR_INSTALLED, "false");
}
if (ustate.stopped) {
//XML标记：stopped
serializer.attribute(null, ATTR_STOPPED, "true");
}
if (ustate.notLaunched) {
//XML标记：nl
serializer.attribute(null, ATTR_NOT_LAUNCHED, "true");
}
if (ustate.blocked) {
//XML标记：
serializer.attribute(null, ATTR_BLOCKED, "true");
}
if (ustate.enabled != COMPONENT_ENABLED_STATE_DEFAULT) {
//XML标记：enabled
serializer.attribute(null, ATTR_ENABLED,
Integer.toString(ustate.enabled));
if (ustate.lastDisableAppCaller != null) {
//XML标记：enabledCaller
serializer.attribute(null, ATTR_ENABLED_CALLER,
ustate.lastDisableAppCaller);
}
}
if (ustate.enabledComponents != null
&& ustate.enabledComponents.size() > 0) {
//XML标记：enabled-components
serializer.startTag(null, TAG_ENABLED_COMPONENTS);
for (final String name : ustate.enabledComponents) {
//XML标记：item
serializer.startTag(null, TAG_ITEM);
//XML标记：name
serializer.attribute(null, ATTR_NAME, name);
//XML标记：item
serializer.endTag(null, TAG_ITEM);
}
//XML标记：enabled-components
serializer.endTag(null, TAG_ENABLED_COMPONENTS);
}
if (ustate.disabledComponents != null
&& ustate.disabledComponents.size() > 0) {
//XML标记：disabled-components
serializer.startTag(null, TAG_DISABLED_COMPONENTS);
for (final String name : ustate.disabledComponents) {
serializer.startTag(null, TAG_ITEM);
serializer.attribute(null, ATTR_NAME, name);
serializer.endTag(null, TAG_ITEM);
}
serializer.endTag(null, TAG_DISABLED_COMPONENTS);
}
//XML标记：pkg
serializer.endTag(null, TAG_PACKAGE);
}
}
writePreferredActivitiesLPr(serializer, userId, true);
serializer.endTag(null, TAG_PACKAGE_RESTRICTIONS);
serializer.endDocument();
str.flush();
FileUtils.sync(fstr);
str.close();
// New settings successfully written, old ones are no longer
// needed.
backupFile.delete();
FileUtils.setPermissions(userPackagesStateFile.toString(),
FileUtils.S_IRUSR|FileUtils.S_IWUSR
|FileUtils.S_IRGRP|FileUtils.S_IWGRP,
-1, -1);
// Done, all is good!
return;
} catch(java.io.IOException e) {
Log.wtf(PackageManagerService.TAG,
"Unable to write package manager user packages state, "
+ " current changes will be lost at reboot", e);
}
// Clean up partially written files
if (userPackagesStateFile.exists()) {
if (!userPackagesStateFile.delete()) {
Log.i(PackageManagerService.TAG, "Failed to clean up mangled file: "
+ mStoppedPackagesFilename);
}
}
}

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A，该函数主要工作就是写入当前用户的“data/system/users/userId/package-restrictions.xml”

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地板

发表于 2014-1-16 18:35:18 |只看该作者

8，下面我们看看Installer.java中的createUserData函数

public int createUserData(String name, int uid, int userId) {
//发送一个记号为“mkuserdata”的socket通信
StringBuilder builder = new StringBuilder("mkuserdata");
builder.append(' ');
builder.append(name);
builder.append(' ');
builder.append(uid);
builder.append(' ');
builder.append(userId);
return execute(builder.toString());
}

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A，该方法发送了一个记号为“mkuserdata”的socket通信

9，该通信的接收处理方是一个C文件installd.c，我们看看该文件的源码

struct cmdinfo cmds[] = {
{ "ping", 0, do_ping },
{ "install", 4, do_install },
{ "dexopt", 3, do_dexopt },
{ "movedex", 2, do_move_dex },
{ "rmdex", 1, do_rm_dex },
{ "remove", 2, do_remove },
{ "rename", 2, do_rename },
{ "fixuid", 3, do_fixuid },
{ "freecache", 1, do_free_cache },
{ "rmcache", 2, do_rm_cache },
{ "getsize", 6, do_get_size },
{ "rmuserdata", 2, do_rm_user_data },
{ "movefiles", 0, do_movefiles },
{ "linklib", 3, do_linklib },
{ "mkuserdata", 3, do_mk_user_data },
{ "rmuser", 1, do_rm_user },
};
static int do_mk_user_data(char **arg, char reply[REPLY_MAX])
{
return make_user_data(arg[0], atoi(arg[1]), atoi(arg[2])); /* pkgname, uid, userid */
}

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A，该文件定义了若干socket通信命令的处理函数
B，由上我们可知，是调用了installd.c中的do_mk_user_data这个函数，而在这个函数中则调用了commands.c中的make_user_data函数

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5^#

发表于 2014-1-16 18:38:15 |只看该作者

10，我们接着看看commands.c中的make_user_data函数源码

int make_user_data(const char *pkgname, uid_t uid, userid_t userid)
{
//形如"data/user/userId/包名"的路径
char pkgdir[PKG_PATH_MAX];
//形如"data/app-lib"的路径
char applibdir[PKG_PATH_MAX];
//形如"data/user/userId/包名/lib"的路径
char libsymlink[PKG_PATH_MAX];
struct stat libStat;
// Create the data dir for the package
//PKG_DIR_POSTFIX 定义是空
//#define PKG_DIR_POSTFIX ""
if (create_pkg_path(pkgdir, pkgname, PKG_DIR_POSTFIX, userid)) {
return -1;
}
//#define PKG_LIB_POSTFIX "/lib"
if (create_pkg_path(libsymlink, pkgname, PKG_LIB_POSTFIX, userid)) {
ALOGE("cannot create package lib symlink origin path\n");
return -1;
}
//形如"data/app-lib"的路径
if (create_pkg_path_in_dir(applibdir, &android_app_lib_dir, pkgname, PKG_DIR_POSTFIX)) {
ALOGE("cannot create package lib symlink dest path\n");
return -1;
}
//创建新的文件夹，权限-rwxr-x--x
if (mkdir(pkgdir, 0751) < 0) {
ALOGE("cannot create dir '%s': %s\n", pkgdir, strerror(errno));
return -errno;
}
//将新的文件夹权限设置为-rwxr-x--x
if (chmod(pkgdir, 0751) < 0) {
ALOGE("cannot chmod dir '%s': %s\n", pkgdir, strerror(errno));
unlink(pkgdir);
return -errno;
}
if (lstat(libsymlink, &libStat) < 0) {
if (errno != ENOENT) {
ALOGE("couldn't stat lib dir for non-primary: %s\n", strerror(errno));
unlink(pkgdir);
return -1;
}
} else {
if (S_ISDIR(libStat.st_mode)) {
if (delete_dir_contents(libsymlink, 1, 0) < 0) {
ALOGE("couldn't delete lib directory during install for non-primary: %s",
libsymlink);
unlink(pkgdir);
return -1;
}
} else if (S_ISLNK(libStat.st_mode)) {
if (unlink(libsymlink) < 0) {
ALOGE("couldn't unlink lib directory during install for non-primary: %s",
libsymlink);
unlink(pkgdir);
return -1;
}
}
}
//让新用户的App中的lib文件指向"data/app-lib"文件中的lib
if (symlink(applibdir, libsymlink) < 0) {
ALOGE("couldn't symlink directory for non-primary '%s' -> '%s': %s\n", libsymlink,
applibdir, strerror(errno));
unlink(pkgdir);
return -1;
}
if (selinux_android_setfilecon(pkgdir, pkgname, uid) < 0) {
ALOGE("cannot setfilecon dir '%s': %s\n", pkgdir, strerror(errno));
unlink(libsymlink);
unlink(pkgdir);
return -errno;
}
if (chown(pkgdir, uid, uid) < 0) {
ALOGE("cannot chown dir '%s': %s\n", pkgdir, strerror(errno));
unlink(libsymlink);
unlink(pkgdir);
return -errno;
}
return 0;
}

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A，该函数中首先创建形如"data/user/userId/包名"的路径
B，然后创建形如"data/user/userId/包名/lib"的路径
C，在data/app-lib目录下创建相应目录
D，设置"data/user/userId/包名"目录的权限是0751，-rwxr-x--x
E，让新用户的"data/user/userId/包名/lib"文件指向"data/app-lib"文件中的lib

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